Air separation pre-cooling system capable of preventing scaling

Abstract

The utility model discloses an anti-scaling air separation precooling system, which comprises an air cooling tower, a water cooling tower and a circulating water inlet header pipe, the circulating water inlet header pipe is respectively connected with the air cooling tower and the water cooling tower through a first circulating water inlet branch pipe and a second circulating water inlet branch pipe, the second circulating water inlet branch pipe is connected with a fresh water inlet pipe, and the fresh water inlet pipe is connected with a fresh water outlet pipe. A flow meter, a filter and a fresh water regulating valve are mounted on the fresh water inlet pipe; the bottom of the water cooling tower is connected with a chilled water pipe, and the end, away from the water cooling tower, of the chilled water pipe is connected with the top of the air cooling tower. The air separation precooling system capable of preventing scaling has the advantages of being capable of preventing scaling and low in cost.

Description

Technical Field

[0001] The utility model belongs to the technical field of air separation equipment, and in particular relates to an air separation precooling system for preventing scaling. Background Art

[0002] At present, the air separation process usually uses cryogenic distillation to produce oxygen and high-purity nitrogen products. The air needs to go through compression, precooling, purification, liquefaction and distillation processes. During the precooling process, an air cooling tower and a water cooling tower are set up, and industrial circulating water is used to exchange heat with the air to cool and wash the air. A water circulation system is adopted between the air cooling tower and the water cooling tower. In the lower part of the air cooling tower, the compressed air and the circulating water are in direct contact for heat exchange, and in the upper part of the air cooling tower, the air and the low-temperature water are in direct contact for heat exchange. The current problem is that the increase in water temperature will cause the calcium and magnesium ions in the circulating water to precipitate and scale in the air cooling tower filler. In addition, in the pipes and equipment connected to the water cooling tower, the circulating water is cooled, resulting in low-temperature crystallization in the precooling system, blocking the filler, pipes, heat exchangers and air cooling tower spray holes, thereby causing a decrease in water flow and an increase in air temperature. In severe cases, carbon dioxide penetration occurs in the subsequent molecular sieve purification system, the low-temperature heat exchanger in the air separation cold box is blocked, and the air separation is shut down.

[0003] In order to solve the scaling and crystallization problems of air separation precooling system, the existing technology usually adopts the method of adding special agents to circulating water to prevent scaling. For example, patent CN 09133386A discloses a method for treating circulating cooling water, which uses fresh water as air cooling circulating water, and solves the scaling and corrosion problems of air precooling system and circulating cooling water system by changing the water replenishment point of fresh water and reasonably adding scale and corrosion inhibitors. The dosing process of this technology is complicated, the operation and maintenance are inconvenient, special agents need to be used, and the cost is high.

[0004] In addition, there are other treatment methods in the prior art, such as patent CN 206113696U discloses an oxygen-generating air separation precooling system, which cleans the precooling system online by setting a cleaning agent water tank, thereby gradually removing the scaling in the precooling system. However, this technology is intended to treat the already scaled circulating water system afterwards, and cannot prevent high-temperature scaling or low-temperature crystallization of the water system. Utility Model Content

[0005] In view of this, the purpose of the utility model is to provide an air separation precooling system that prevents scaling, so that it has the advantages of being able to prevent scaling and low cost.

[0006] The utility model solves the above-mentioned problem through the following technical means: an air separation precooling system for preventing scaling, comprising an air cooling tower, a water cooling tower and a circulating water inlet main pipe, wherein the circulating water inlet main pipe is connected to the air cooling tower and the water cooling tower through a first circulating water inlet branch pipe and a second circulating water inlet branch pipe respectively, the second circulating water inlet branch pipe is connected to a fresh water inlet pipe, and a flow meter, a filter and a fresh water regulating valve are installed on the fresh water inlet pipe; a chilled water pipe is connected to the bottom of the water cooling tower, and an end of the chilled water pipe away from the water cooling tower is connected to the top of the air cooling tower.

[0007] Furthermore, a check valve is provided at the connection between the fresh water inlet pipe and the second circulating water inlet branch pipe.

[0008] Furthermore, a cooling water pump is installed on the first water inlet branch of the circulating water.

[0009] Furthermore, a circulating water regulating valve is installed on the second circulating water inlet branch pipe.

[0010] Furthermore, a chilled water pump and a chiller are installed on the chilled water pipe.

[0011] Furthermore, an air inlet pipe is connected to one side of the air cooling tower near the bottom, an air exhaust pipe is connected to the top of the air cooling tower, and a circulating water return pipe is connected to the bottom of the air cooling tower.

[0012] Furthermore, a dirty nitrogen gas inlet pipe is connected to one side of the water cooling tower.

[0013] Beneficial effects of the utility model:

[0014] By adding a fresh water inlet pipe to the water cooling tower inlet line, adding fresh water, and then controlling the fresh water flow through the fresh water regulating valve, the concentration of calcium and magnesium ions entering the water cooling tower circulating water is reduced. No low-temperature crystals will be formed during the cooling process of the circulating water, and there will be no low-temperature scaling. The pre-cooling system will no longer be blocked to affect the operation of the air separation. At the same time, the added fresh water can be used as water for the circulating water station, and the water replenishment volume of the circulating water station has not been increased. The circulating water station is replenished and dosing is carried out according to conventional standards, and no special corrosion and scale inhibitors are required, which reduces the treatment cost and dosing cost of the entire air separation circulating water station. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0016] Figure 1 This is a schematic diagram of an air separation precooling system for preventing scaling according to an embodiment of the utility model. DETAILED DESCRIPTION

[0017] The present invention will be further described below through the accompanying drawings and embodiments, which are not intended to further limit the content of the present invention. Those skilled in the art should understand that equivalent replacements or corresponding improvements made to the technical features of the present invention still fall within the scope of protection of the present invention.

[0018] like Figure 1 As shown, the air separation precooling system for preventing scaling of this embodiment includes an air cooling tower 3, a water cooling tower 19 and a circulating water inlet main pipe 9, the circulating water inlet main pipe is connected to the air cooling tower and the water cooling tower through a first circulating water inlet branch pipe 6 and a second circulating water inlet branch pipe 8 respectively, the second circulating water inlet branch pipe is connected to a fresh water inlet pipe 10, and a flow meter 11, a filter 12 and a fresh water regulating valve 13 are installed on the fresh water inlet pipe; the bottom of the water cooling tower is connected to a chilled water pipe 5, and the end of the chilled water pipe away from the water cooling tower is connected to the top of the air cooling tower.

[0019] A check valve 14 is provided at the connection between the fresh water inlet pipe and the second circulating water inlet branch. A cooling water pump 7 is installed on the first circulating water inlet branch. A circulating water regulating valve 15 is installed on the second circulating water inlet branch. A chilled water pump 16 and a chiller 17 are installed on the chilled water pipe. An air intake pipe 2 is connected to one side of the air cooling tower near the bottom, an air exhaust pipe 4 is connected to the top of the air cooling tower, and a circulating water return pipe 1 is connected to the bottom of the air cooling tower. A dirty nitrogen inlet pipe 18 is connected to one side of the water cooling tower.

[0020] During specific operation, fresh water flows in from the fresh water inlet pipe, is filtered by the filter, the flow rate of fresh water is measured by the flow meter, and then the flow rate is adjusted to the set value by the fresh water regulating valve. Generally speaking, the ratio of fresh water to circulating water is 1:1-3. Preferably, a check valve is provided to prevent the circulating water from returning to the fresh water inlet pipe; the fresh water is mixed with the circulating water from the second inlet branch of the circulating water, and then enters from the top of the water cooling tower, and the dirty nitrogen from the air separation cold box enters from the bottom of the water cooling tower through the dirty nitrogen inlet pipe, and is countercurrently contacted with the water for heat exchange, and the dirty nitrogen is released from the top, so that the water is cooled; the cooled water is drawn out from the bottom of the water cooling tower, and after being pressurized by the chilled water pump and cooled to a suitable temperature again by the chilled water unit, the chilled water enters from the top of the air cooling tower to cool the processed air from the air compressor (the air flows in through the air inlet pipe), and the cooled air is discharged from the air exhaust pipe at the top of the air cooling tower and enters the molecular sieve purification system. The circulating water from the first circulating water inlet branch is pressurized by the cooling water pump and enters the middle of the air cooling tower to cool the air. The heated circulating water enters the bottom of the air cooling tower together with the upper chilled water, and is discharged to the circulating water station for circulation treatment through the circulating water return pipe; the water from the circulating water inlet main is provided by the circulating water station. The circulating water regulating valve is used to keep the liquid level of the water cooling tower stable.

[0021] In summary, the air separation precooling system for preventing scaling of the present application reduces the concentration of calcium and magnesium ions in the circulating water entering the water cooling tower by adding a fresh water inlet pipe to the water cooling tower inlet line, replenishing fresh water, and then controlling the fresh water flow rate through a fresh water regulating valve. No scaling will occur during the cooling process of the circulating water, and no clogging of the precooling system will occur to affect the operation of the air separation. The fresh water added at the same time can be used as water replenishment for the circulating water station without increasing the water replenishment amount of the circulating water station. The circulating water station is replenished and dosing is carried out according to conventional standards, and no special corrosion and scale inhibitors are required, which reduces the processing cost and dosing cost of the entire air separation circulating water station.

[0022] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. An air separation precooling system for preventing scaling, characterized in that: It includes an air-cooling tower, a water-cooling tower and a circulating water inlet main pipe. The circulating water inlet main pipe is connected to the air-cooling tower and the water-cooling tower through a first circulating water inlet branch pipe and a second circulating water inlet branch pipe respectively. The second circulating water inlet branch pipe is connected to a fresh water inlet pipe. A flow meter, a filter and a fresh water regulating valve are installed on the fresh water inlet pipe. A chilled water pipe is connected to the bottom of the water-cooling tower, and the end of the chilled water pipe away from the water-cooling tower is connected to the top of the air-cooling tower.

2. The air separation precooling system for preventing scaling according to claim 1, characterized in that: A check valve is provided at the connection between the fresh water inlet pipe and the second circulating water inlet branch pipe.

3. The air separation precooling system for preventing scaling according to claim 2 is characterized in that: A cooling water pump is installed on the first water inlet branch of the circulating water.

4. The air separation precooling system for preventing scaling according to claim 3 is characterized in that: A circulating water regulating valve is installed on the second circulating water inlet branch pipe.

5. The air separation precooling system for preventing scaling according to claim 4 is characterized in that: A chilled water pump and a chiller are installed on the chilled water pipe.

6. The air separation precooling system for preventing scaling according to claim 5 is characterized in that: An air inlet pipe is connected to one side of the air cooling tower near the bottom, an air exhaust pipe is connected to the top of the air cooling tower, and a circulating water return pipe is connected to the bottom of the air cooling tower.

7. The air separation precooling system for preventing scaling according to claim 6 is characterized in that: One side of the water cooling tower is connected with a dirty nitrogen gas inlet pipe.

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